Recently, a high temperature rapid development processing of silver halide photographic materials has become more widely used, and the processing using an automatic developing machine has been shortened remarkably. In order to attain rapid processing, a photographic material is needed having a high development rate to yield a sufficient blacking density in a short period of time and the ability to be fixed, rinsed and dried in a short period of time. In particular, various methods have heretofore been investigated for attaining rapid drying of processed photographic materials. A method well adapted for improving the driability of processed photographic materials is known in which a sufficient amount of a hardening agent (gelatin crosslinking agent) is previously added to a photographic material in the coating step of preparing the same so as to reduce the swelling rate of the constituent emulsion layer and hydrophilic colloid layer during development, fixation and rinsing. As a result, the water content of the processed photographic material prior to drying is reduced. In accordance with this method, the addition of a larger amount of the hardening agent further reduces the drying time. However, the swelling rate of the constituent layers is lowered to the extent that development of the material is retarded, to thereby reduce sensitivity and contrast or to effectively reduce covering power.
Apart from the above, another rapid processing method is known, for example, as described in JP-A-63-136043 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"), in which a developer and a fixer each having substantially no gelatin-hardening effect are used. This method advantageously promotes the rate of development and the rate of fixation using the processing solutions having substantially no gelatin hardening effect, while the rate of drying is reduced. Therefore, this method is not considered to be sufficiently effective.
On the other hand, as a method of promoting the rate of development and enhancing covering power, the addition of various additives to silver halides is known. Such additives include, for example, the polyacrylamide polymer additives as disclosed in U.S. Pat. Nos. 3,271,158 and 3,514,289; and dextran compounds such as saccharide additives as disclosed in U.S. Pat. Nos. 3,063,838 and 3,272,631. However, where these compounds are added to photographic materials in an amount sufficient to satisfy the above objects, the driability of the materials and the film strength thereof are deteriorated.
In addition, other methods are known for elevating the developing activity of a developer, in which the amount of the developing agent and that of the developing aid in the developer are increased, the pH value of the developer is elevated, and the developer processing temperature is elevated. However, all of these methods have various drawbacks in that the preservability of the developer is reduced, the contrast of the processed material is lowered or softened even though the sensitivity thereof is elevated, and the processed material is readily fogged.
Apart from rapid processability, further elevation of the sensitivity and covering power of photographic materials is an objective heretofore sought in this technical field. Where an increase in sensitivity of photographic materials is realized by enlarging the grain size of silver halide grains therein, the covering power of the grains is generally lowered. Therefore, if increased sensitivity of photographic materials could not be attained by using silver halide grains having the same grain size, or if increased covering power thereof could not be attained by using silver halide grains of the same sensitivity, then such would not constitute a significant advance in the art.